The present invention relates to boat hoists and more particularly, a boat hoist system that uses a hydraulic drive unit.
Boat hoists are, of course, known. Generally boat hoists will consist of a stationary frame member and a movable frame member, with the movable frame member being movable from an unload down (underneath the water) position to a loaded raised position (above the water). Such units must, of course be durable and be able to withstand significant environmental challenges such as constant exposure to water and sun, etc.
The operation to move such units from the unload down position to the loaded up position can take a variety of forms. For example, there have been systems in the past that raise and lower straight up and down. There have been systems that raise or lower on a slant or an angle, and there have been systems that raise or lower using rotational or pivotal movement to define a raise and lower arcuate path. All generally use some sort of cable system operable by a winch and a transmitting force, either manually (individuals wind them up or down) or electrically driven wherein a motor provides the power transmitting force.
When an electric motor is used, there must, of course, be an available electrical hook up. Such is typically provided via shore line electrical outlets and long cords, usually extending out along a dock to the boat hoist. This transmission of fairly low voltage home electrical power to the boat hoist over fairly long distances often results in loss of power. As a result, and as boats have gotten inevitably bigger, larger, and heavier, the efficiency of such units has decreased. For example, with currently available systems operating a raise/lower drive bar with a winding cable can typically raise or lower a boat in from four to six minutes. With this length of time required, many people often choose to forego electric power driven units and simply purchase hand units, using a hand rotated wheel, a winch and pulley system.
In the past, people have not looked to hydraulic drive units because of the natural tendency for hydraulic cylinder and its associated extendible arm to twist under pressure causing damage to the unit. Also, hydraulic units under water present a risk of damage both to the hydraulic unit and to the environment if they leak oil.
In can be seen, therefore, that especially for fresh water lake boat hoists, there is a continuing need for improvements in the means of transmitting the power or force to the boat hoist. Those in the manufacturing business recognize this need but have not yet achieved an attainable, practical resolution to the problem.
Accordingly, it is a primary object of this invention to provide an improved boat hoist which is operable on lower voltage requirements to achieve more efficient raising and lowering of even heavy boats at faster speeds.
Another object of this invention is to provide a boat hoist achieving the primary objective but using hydraulic driven units for greater load and unload efficiency.
A further object of the present invention is to achieve the above with hydraulic units attached in such a manner to prevent the natural twisting action of the hydraulic unit in operation, and attached so they are not ever under water, and using vegetable oil as the hydraulic fluid to avoid oil leakage into fresh water.
A further object of the present invention is to achieve the above with a unit design that can be used to retrofit existing units if one wishes to remove current conventional drive systems and replace those with hydraulic systems of the present invention.
The method of achieving each of the above, as well as other objectives will become apparent from the following detailed description of the invention which will be described with continuing reference to the drawings.